Interest-computing device



Nov. 12, 1957 S. H. KANTROWITZ INTEREST-COMPUTING DEVICE Firm April 28,1954 FIG JUN JULY Nov] m MAR APR MAY AUG SEPT OCT milzismsmwmmm nuuumim$mssm$$m mlmssitmmfimHHzHl mmmmmszmmmms mmasimmmflmsmm smmwMHHHMHIumnsmmmmamm;

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IN V EN TOR.

ATTORNEY United States Patent INTEREST-COMPUTING DEVICE Sidney H.Kantrowitz, Teaneck, N. J.

Application April 28, 1954, Serial No. 426,112 11 Claims. (Cl. 235-89)The present invention relates to calculators, and particularly tocomputing devices by which interest and dividend factors per dollar of aprincipal sum may be obtained for a period of time designated inconventional calendar notations.

Calculators are known for obtaining interest factors for a period oftime designated as a given number of days, months and years. An interestor dividend payment is then computed by multiplying the obtainedinterest factor times the principal amount. These known devices exhibita number of drawbacks, prominently the need for the operator to computetime independently and before ascertaining the interest factor throughuse of the device. Stated differently, the operator must transpose atime period expressed by a period-start date having a day,

month and year notation, and a period-end date, likewise having a day,month and year notation, to a definite number of years, months and days.Further, devices requiring a transposition to a given number of years,months and days for the period under consideration, frequently producethree separate subfactors, a first corresponding to the number of years,a second to the number of months, and a third to the number of days.These subfactors must be added to obtain the interest factor. Stillfurther, some of these known devices utilize the concept of obtainingfactors for ones, tens, hundreds and thousands designations of aprincipal sum and performing additional arithmetic operations to arriveat the final interest or principal payment.

It is an object of the present invention to provide an improved interestand dividend computing device obviating one ormore of the aforesaiddifiiculties. Specifically, it is within the contemplation of thepresent invention to provide computing devices by which interest factorsmay be obtained without the need for preliminary breaking down of a timeperiod into its corresponding numbers of years, months and days.

It is a further object of the present invention to provide a computingdevice for ascertaining interest or dividend factors for a period oftime, such that a final interest or dividend payment for said period maybe ascertained by merely multiplying the interest factor times theprincipal sum.

It is a still further object of the present invention to provide aninterest-computing device which is inherently simple, and may be usedwith standard oflice computing equipment to arrive at interest anddividend factors for principal sums. Advantageously, by simple manualmanipulation, an operator can obtain an interest factor for a period oftime and use a computing machine to arrive at the final interest ordividend payment for said period, with extreme accuracy and minimumexpenditure of time and effort.

In accordance with an illustrative embodiment demonstrating features andaspects of the present invention, an interst-computing device isinitially set up for computing interest or dividend factors at a giveninterest or dividend rate. The device includes a chart holder havingachartframing opening, and an interest factor chart at said giveninterest rate having first and second sets of interest factor columns,with the columns of each set having day-by-day interest factors for aperiod of one month. The columns of the first set are laterally offsetby one column relative to the columns of the second set, such thatsequential reading from month to month throughout the chart may beaccomplished. Means are associated with the chart and holder forestablishing period-start notations and period-end notations, eachexpressed as a month and day, with appropriate provision for reading theinterest factor for the period covered by said notations.

The facility in operation, as well as further objects, features andadvantages of the present invention, will be best appreciated byreference to the following detailed description of a presently preferredembodiment, when taken in conjunction with the accompanying drawings,wherein:

Fig. 1 is a plan view, approximately to size and with portions foldedback for clarity, showing an interest computing device embodyingfeatures of the present invention;

Fig. 2 is a sectional view taken substantially along the line 2-2 ofFig. 1 and looking in the direction of the arrows;

Fig. 3 is a fragmentary plan view showing the arrangement of the monthselector on the front face of the chart holder; and

Fig. 4 is a plan view of a 6% interest factor chart illustratingfeatures of the present invention.

Specific reference will now be made to the drawings, wherein there isshown an interest computing chart in ac- 'cordance with the presentinvention which includes a chart holder or body 10 and interestcomputing charts 12 contained therein. Although only one interestcomputing chart is shown in the illustrative embodiment, it is to beappreciated that a set of charts or cards would be provided with eachchart holder, each chart being set up for computing interest factors ata particular rate of interest.

The chart holder 10 includes front and rear rectangular walls 14, 16which are spaced apart and substantially coextensive in size. The wallsor panels 14, 16 made of any suitable paper or plastic material, arearranged to define a longitudinally extending channel or guideway 18therebetween for accommodating therein one or more of the interestfactor charts 12. In the illustrative form of the invention, the panels14, 16 are joined by an upper end wall 20 and one side wall 22. Thepanel may be joined by side walls such that charts are inserted fromeither open end.

The front wall or panel 14 of the chart holder or body 10, is formedwith a chart-framing opening or field 24. The size of the rectangularchart-framing opening is selected in accordance with the columnarrangement of the interest computing chart 12. The width of the opening24 corresponds to twelve column widths, while the height of the opening24 depends upon the vertical spacing of the interest factors in therespective columns, and is such that thirty vertically-disposed factorsmay be framed therein.

A period-start column 26 is arranged along the left vertical side edgeof the chart-framing opening 24 and includes consecutive numbers fromone to thirty corresponding to the days of the month. The numbers of theperiod-start column are arranged in an increasing series readingdownwardly along the vertical side edge of the chart-framing opening 24and serves as references in selecting interest factors, as willsubsequently be described.

Slidably mounted on the chart holder or body 10 is a month selectorslide 28 which is in the form of a sleeve and has a transversely orhorizontally extending window 30 in the front wall thereof. The window30 is arranged to selectively frame rows of a month selector chart'32,illustrated in Fig. 3. The month selector chart 32 includes monthdesignations or indicia on the front panel 14 of the body at locationsspaced above the chart-framing opening. The selector 32 is oriented inrelation to the respective vertical columns framed by the opening 24 andinclude twelve horizontal rows of month designations. Each of the rows,when selected, provides month headings for the vertical columns of theinterest factor chart. The successive rows of the month selector 32begin with successive months of the year, such Lhat headings may beprovided for the columns starting from any given month of the year andreading from left to right. For example, in the slide positionillustrated in Fig. 1, the window frames the sixth horizontal row of theindicia 32 and gives month headings for the chart columns beginning fromthe month of June and reading consecutively to the month of May, fromleft to right. a

Reference will now be made to Fig. 4, wherein there is shown the detailsof a chart 12 having day by day 6% interest factors. The chart 12includes a datum or reference line 34 extending horizontally of thechart and dividing the chart 12 into an upper-half section 12a and alower-half section 1212. In the upper-half section 12a is a first set ofinterest factor columns which extend above the datum line 34, and in thelower half section 1217 is a second set of interest factor columnsextending below the datum line. The interest factor columns in each ofthe sets or half-sections of the chart have day by day interest factorswhich are disposed in sequence for reading up successive columns of therespective sets. For example, the right margin column A of the lowerhalf section 12b has interest factors beginning from the smallest factorof .00017, corresponding to the single day factor at 6%, and increasingby day increments to the uppermost factor of .00483. The next factor insequence corresponds to the interest factor for one month or thirtydays, namely .005 or one-half of one percent, and lies along the datumor reference line 34.

The columns of the respective interest factor sets are laterally offsetby one column such that an aligned pair of columns composed of one fromeach set have interest factors disposed in sequence when reading up thealigned pairs of columns. As an example, interest factor column A at theright-hand margin of the lower-half section 12b, is identical to columnA at the left hand margin of the upper-half section 12a. It will beappreciated that the columns A and A correspond to interest factors fora first thirty day period or the first month. Identical columnscorresponding to a second thirty day period or the second month arerespectively designated by the letters B and B. The column'B is nextadjacent to the column A in the lower-half section 12b of the chart 12,while its identical column B is next adjacent to column A in theupper-half section 12a. The laterally offset column arrangement is suchthat reading up the columns A, B interest factors may be read insequence for a period of two months. The symmetry of the chart, and thearrangement of the remainder of the columns should be apparent by visualinspection and from the foregoing description.

Along one side of the 6% interest chart 12 is a periodend column 36which has consecutive numbers corresponding to the days of the month, asin the period-start column 26. The numbers of the period-end column 36are arranged in an increasing series reading upwardly from the vicinityof the datum line 34 such that any day in a period end notation may beselected.

In the front panel or wall 14 of the chart holder 10, there is formed awindow 38 for selectively framing the numbers or indicia of theperiod-end column 36. The window 38 is oriented in relation to thebeginning of the period-start column 26 as the period-end column 36 isoriented relative to the datum or reference line 34. Specifically, thewindow 38 is opposite the period-start designation 3, whereas theperiod-end column 36 is disposed such that the designation 3 is directlyalong the datum line 34.

The function of the illustrated device will be best appreciated byconsidering a typical problem. If, for example, the interest factor at6% from a period-start date of February 12 of a given year through aperiodend date of June 27 of said given year is to be obtained, thefollowing manipulations are performed.

The month selector slide 28 is vertically displaced in relation to thechart body 10 such that the window 30 frames the sixth row of themonth-heading indicator 32, that is the row beginning with the monthheading June. Thus, the headings for the factor chart columns will beginwith June, the month of the period-end notation, reading from left toright. The 6% chart is vertically displaced within the guide orchannelway 18 until the day of the month that the interest is to becomputed to appears in the window 38. After this sliding movement, thechart 12 is in relation to the chart-forming opening 24 such that therespective interst factor columns have the required month headings ordesignations which are visually observed through the window 30. As shownin Figs. 1 and 3, the interest chart is set for computing interest fromthe period-end date of June 27 of a given year, to any period-start datewithin that year. In the selected example, the period-start date isFebruary l2'and accordingly, the operator looks down the columns of theframed portion of the interest chart headed by the month designationFebruary. In this column, the operator selects the interest factorappearing opposite the day designated 12 in the period-start column 26,as indicated by arrows, and reads the interest factor .0225. This factorindicates the interest at 6% for the stated period based upon theprincipal sum of $1.00. Thereupon, it is merely necessary to multiplythe dollars and cents of a given principal sum by this factor to arriveat an interest or dividend payment.

For determining discounts, it will be appreciated that the outlinedprocedure is reversed, that is the month designation to which thediscount is to be computed is set in the window 30 of the month selectorslide 28, and the day designation is arranged to appear in window 38 ofthe chart body 10.

As a further feature of the invention, the chart body 10 is providedwith indicia facilitating use of the chart when the number of days in aperiod is known. For this purpose along the lower horizontal edge of thechart framing window 24, there is provided designations or headings forsuccessive thirty day periods, arranged from right to left along thetwelve columns of the chart-framing opening 24. When the number of daysis known or is easily ascertainable, it is merely necessary to slide theinterest-computing chart 12 to a longitudinal position wherein thenumber appearing in window 38 corresponds to the number of days inexcess of multiples of thirty for the period. The interest factors forthis number of days is read in the last visible line of the chart,corresponding to the horizontal line opposite numeral 30 of theperiod-start column 26 and underlined by the lower horizontal edge ofthe opening 24. Specifically, the chart in Figs. 1 and 3 is set to readan interest factor for twenty-seven days, or factor twenty-seven days inexcess of multiples of thirty. For. example, reading in the horizontalline opposite the numeral 30, the interest factor for twenty-seven daysis .0045; further, for two hundred and seven days, the interest factoris .0345. As previously stated, these factors may be used with anyprincipal sums for interest and dividend calculations.

It will be appreciated that greater accuracy may be obtained byextending the accuracy of the interest factors [11 the chart to morethan five places.

The many advantages and facility of the present interestcomputing deviceshould be apparent from the foregoing description. The device ischaracterized in that the period-start and period-end designations areexpressed in conventional day and month notation, and may be used as abasis for computing an interest factor for a given period without theneed for transposition to a given number of days and months. The thusobtained interest factor is but a single number and in turn may bemultiplied with any principal sum or amount to ascertain interest ordividend. Further applications of the device will be apparent to thoseacquainted with the business fields and numerous applications are to befound in banking, discount and installment credit operations.

Numerous modifications of the device of the present invention will occurto those skilled in the art, and accordingly the appended claims shouldbe given a latitude of interpretation consistent with the disclosure andat times certain features of the invention will be used without acorresponding use of other features.

What I claim is:

1. An interest computing device comprising a chart holder, at least onechart having first and second sets of interest factor columns, thecolumns of each set having day by day interest factors for a period ofone month with the columns of said first set being laterally offsetrelative to the columns of said second set whereby an aligned pair ofcolumns has consecutive day by day interest factors, a period-startcolumn on said chart holder having consecutive numbers corresponding tothe days of the month, a period-end column on said chart havingconsecutive numbers corresponding to the days of the month, andperiod-end day selector means on said chart holder disposed inpredetermined relation to said periodstart and period-end columns.

2. An interest computing device comprising a chart holder having achart-framing opening, at least one chart having first and second setsof interest factor columns one of which extends above a datum line andthe other of which extends below said datum line, the columns of eachset having day by day interest factors for a period of one month withthe columns of said first set being laterally offset by one columnrelative to the columns of said second set, a period-start column onsaid chart holder having consecutive numbers corresponding to the daysof the month, a period-end column on said chart in predeterminedrelation to said datum line and having consecutive numbers correspondingto the days of the month, and a period-end day selector window on saidchart holder in predetermined relation to said period-start column.

3. An interest computing device comprising a chart holder having achart-framing opening, a chart having first and second sets of interestfactor columns one of which extends above a datum line and the other ofwhich extends below said datum line, the columns of each set having dayby day interest factors for a period of one month, the columns of saidfirst set being laterally offset by one column relative to the columnsof said second set whereby consecutive interest factors may be read inan aligned column pair, a period-start column on said chart holderhaving consecutive numbers corresponding to the days of the month, aperiod-end column on said chart having consecutive numbers correspondingto the days of the month, and a period-end day selector window in saidchart holder disposed in predetermined relation to said period-start andperiod-end columns, said period-end column having its numbers arrangedin an increasing series extending upwardly from said datum line inparallel relation to said interest factor columns.

4. An interest computing device comprising a chart holder including achart-framing opening having an upper edge, at least one chart havingfirst and second sets of interest factor columns one of which extendsabove a datum line and the other of which extends below said datum line,the columns of each set having day by day interest factors for a periodof one month with the columns of said first set being laterally offsetby one column relative to the columns of said second set, a period-startcolumn on said chart holder having consecutive numbers corresponding tothe days of the month, a period-end column on said chart havingconsecutive numbers corresponding to the days of the month, and aperiod-end day selector window in said chart holder disposed inpredetermined relation to said period-start and period-end columns, saidperiod-start column having its numbers arranged in an increasing seriesextending downwardly from said upper edge of said chart-framing opening,and said period-end column having its numbers arranged in an increasingseries extending upwardly from said datum line.

5. An interest computing device comprising a chart holder having achart-framing opening, and at least one chart having a datum line, afirst set of interest factor columns extending below said datum line, asecond set of interest factor columns extending above said datum line,the interest factor columns of each of said sets having day by dayinterest factors which are disposed in sequence for reading upsuccessive columns of the respective sets, the columns of said setsbeing laterally offset by one column whereby an aligned pair of columnscomposed of one from each set have interest factors disposed in sequencefor reading up the aligned pair.

6. An interest computing device comprising a chart holder having achart-framing opening, and at least one chart having a datum line, afirst set of interest factor columns extending. below said datum line, asecond set of interest factor. columns extending above said datum line,the interest factor columns of each said sets having day by day interestfactors which are disposed in sequence for reading up successive columnsof the respective sets, the columns of said sets being laterally offsetby one column whereby an aligned pair of columns composed of one fromeach set have interest factors disposed in sequence for reading up thealigned pair, a period-start column on said chart holder havingconsecutive numbers corresponding to the days of the month, the numbersof said period-start column being arranged in an increasing seriesreading downwardly along one side of said chartframing opening, and aperiod-end column on said chart having consecutive numbers correspondingto the days of the month, the numbers of said period-end column beingarranged in an increasing series reading upwardly from said datum line.

7. In an interest computing device, a chart having a datum line, a firstset of interest factor columns extending below said datum line, a secondset of interest factor columns extending above said datum line, theinterest factor columns of each of said sets having day by day interestfactors which are disposed in sequence for reading up successive columnsof the respective sets, the columns of said sets being laterally offsetby one column whereby an aligned pair of columns composed of one fromeach set have interest factors disposed in sequence for reading up thealigned pair.

8. An interest computing device comprising a chart holder having achart-framing opening, and at least one chart having a datum lineslidably supported in said chart holder, a first set of interest factorcolumns extending below said datum line, a second set of interest factorcolumns extending above said datum line, the interest factor columns ofeach of said sets having day by day interest factors which are disposedin sequence for reading up successive columns of the respective sets,the columns of said sets being laterally offset by one column whereby analigned pair of columns composed of one from each set have interestfactors disposed in sequence for reading up the aligned pair, aperiod-start column on said chart holder having consecutive numberscorrespond- A r a 7 r ing to the days of the month, the numbers of saidperiodstart column being arranged in an increasing series readingdownwardly along one side of said chart-framing open ing, and aperiod-end column on said chart having consecutive numbers correspondingto the days of the month, the numbers of said period end column beingarranged in an increasing series reading upwardly from said datum line,and a period-end selector window on said chart holder for selectivelyframing a number of said periodend column in response to slidabledisplacement of said chart relative to said chart holder.

9. A device for reading an interest factor for a time interval fromperiod-start to period-end dates comprising a chart holder having achart-framing opening, and at least one chart having a datum line, afirst set of interest factor columns extendingbelow said datum line, asec ond set of interest factor columns extending above said datum line,the interest factor columns of each of said sets having day by dayinterest factors which are disposed in sequence for reading upsuccessive columns of the respective sets, the columns of said setsbeing laterally offset by one column whereby an aligned pair of columnscomposed of one from each set have interest factors disposed in sequencefor reading up the aligned pair, a periodstart column on said chartholder having consecutive numbers corresponding to the days of themonth, the numbers of said period-start column being arranged in anincreasing series reading downwardly along one side of saidchart-framing opening, and a period-end column on said chart havingconsecutive numbers corresponding to the days of the month, the numbersof said periodend column being arranged in an increasing series readingupwardly in relation to said datum line, and a month selectorselectively oriented in relation to said chart to provide the monthdesignation for the period-end date and for the period-start date.

10. A device for reading an interest factor for a time intervaldesignated by period-start and period-end dates comprising a chartholder having a chart-framing opening, at least one chart having a datumline, a first set of month by month interest factor columns extendingbelow said datum line, a second set of month by month interest factorcolumns extending above said datum line, the interest factor columns ofeach of said sets having day by day interest factors for successivemonths which are disposed in sequence for reading up successive col umnsof the respective sets, the columns of said sets bein laterally offsetby one column whereb an aligned pair of columns composed stone from eachset have interest factors disposed in sequence for reading up thealigned pair, means for orienting said chart in relation to said chartholder for a'selee'ted period-end date, and means for locating theinterest'factor on said chart at a location corresponding to saidperiod-start date.

ll. A device for reading an interest factor for a time period designatedby period start and end dates comprising a chart holder having achart-framing opening, and at least one chart, a first set of interestfactor columns, a second set of interest factor columns, the interestfactor columns of each of's'aid sets having day by day interest factorswhich are disposed in sequence for read ing up successive columns of therespective sets, the columns of said sets being laterally oifset by onecolumn whereby an aligned pair of columns composed of one from each sethave interest factors disposed in sequence for reading up the alignedpair, a period-start column on said chart holder having consecutivenumbers corresponding to the days of the month, the numbers of saidperiodstart column being arranged in an increasing series readingdownwardly along one side of said chart-framing opening, and aperiod-end column on said chart having consecutive numbers correspondingto the days of the month, the numbers of said period-end column beingarranged in an increasing series reading in a direction opposite to saidperiod-start column, a month selector for providing month headings forsaid columns and settable in relation to said chart for providing monthheadings starting with the month designation of the period-end date, anda period-end selector window in said chart holder for selectivelyframing a number of said periodend column in response to slidabledisplacement of said chart relative to said chart holder.

References Cited in the file of this patent UNITED STATES PATENTS294,079 Robinson Feb. 26, 1884 778,790 Merrill Dec. 27, 1904 1,162,828Ammerstol Dec. 7, 1915

